David Harbater, University of Pennsylvania

Lifting branched covers of algebraic curves

Thursday November 17, 4:00PM,
Herman Brown 227

Branched covers of algebraic curves are well understood over
the complex numbers, from the point of view of Riemann surfaces. But
they are more mysterious over other fields, especially in characteristic
p. One approach to studying such covers is to "lift" them to
characteristic 0; this raises the question of which covers can be
lifted, and which covering groups guarantee the existence of a lift.
This talk, which describes joint work with T. Chinburg and R. Guralnick,
considers these questions, which relate to a conjecture of F. Oort.